Improvements in DexronVI over DexronIII

[MileHigh18]

Originally Posted By: MolaKule
Quote:
I have heard of it causing issues for some folks, though I can't imagine why.


Me neither.

The problem I see with some of the "DexronVI caused such as such problem" statements is the lack of a clear, definitive cause-and-effect relationship.

In many cases, some guy finally checks his ATF and discovers it has never been changed, it looks like 100,000 mile diesel oil, and tries to clean up a tranny not shifting properly and most likely on its way out.


Ugh. That may be me. I purchased a used 2002 Trailblazer with 111K on the odometer, and I've swapped all the fluids except the transmission and the cooling system. I'm gonna replace the transmission fluid with DEX VI and the filter, so hopefully I don't have any issues.

 

[Whitewolf]

Originally Posted By: MolaKule
For DexVI, the friction modifier, metal deactivator and antioxidant chemistry's are more stable over a longer time duration.

What this does not mean is the level of additives is higher.

What this does mean is that the shifting performance and overall performance of the fluid will last longer, assuming no internal mechanical or hydraulic problems develop in the transmission.

Improved Metal inhibitors further keep the oil from oxidizing and forming varnishes.


DexVI is also much improved in the area of shear stability.

For a mineral-based Dexron III, the fluid may start out at 7.5 cST and shear down to 4.5 cSt within 30k miles.

For DexronVI, the fluid starts out at 6.0 cSt and may shear down to say 5.7 cSt.

The reason for the improved shear stability is due to two pieces of chemistry:

1. Some formulators use improved and highly stable VII polymers;
2. others use the new HM polymer esters not considered as VII chemistry.

As far as detergency, approximately the same amount of detergent chemistry is available in DexronVI as in DexronIII.

One of the reasons some manufacturers describe their DexronVI's as synthetic blends is that the DexronVI base oils are a mix of GroupIII, IV, and V oils.

The newer friction modifiers are not more "slippery." They have about the same friction coefficients as previous fluids, but are simply more stable over the life of the fluid.

Nearly right,but then I invented it.

 

[MolaKule]

Quote:
Whitewolf: Nearly right,but then I invented it.



I know RF but Nubar over at Afton developed the DexronVI chemistry.

With regards to the White Paper, my opinion is that one has to write in a semi-technical format here on BITOG since this is not the SAE nor is it STLE's Tribology Transactions.

 

[sdowney717]

Originally Posted By: jstutz
Well i am one of those guys that have had issues with dex 6. It was in an 02 blazer that my wife and i bought new. I live around GSO NC so we dont have alot of mountains or anything. My wife primarily drove the blazer to and from work. We also traveled in it so there was a good bit of highway miles on it. Anyway the service history is as follows:

22K - fluid and filter RR with factory fluid
36K - fluid and filter RR with M1 ATF
80K - fluid and filter RR with advance auto brand fluid
115K- fluid and filter RR with M1 ATF
163K- fluid and filter RR with Valvoline Dex6

When draining the M1 out, it looked almost new and i questioned why i change it so often but went ahead with my plan being i bought a case of the DEX 6. I was convinced it was fine. At 183 K miles i have a note in my maintenance log that the transmission fluid looked burnt looking as well as slightly burnt smell. I thought maybe the dex 6 was just cleaning something up or what ever and decided to drive it a bit longer. At 193K miles the fluid was getting worst and i felt like it was slipping a bit ( maybe just panic setting in). I installed a drain plug on the pan and did three drain and fills with WM ST DEX3 until the fluid was nice and red. It now has 215K on it now and the fluid is still looking new.

I dont understand why this happened. The only conclusion i came to is that the fluid is slightly different and maybe my tranny is a little old or the spring are weak but it did not appear to like the Valvoline DEX6.

Just one guys experience. This is a great post because as a engineer, i would really like to understand how this happened or what the root cause was. I know that for the rest of the blazers life it will get ST dEX3 at 30K intervals.


If you have an older transmission, then stick with the older fluid type dex3.
The clutches were slipping with the dex6 causing it to shed and burn material and turn the fluid black.

 

[MolaKule]

Quote:
sdowney717: If you have an older transmission, then stick with the older fluid type dex3.

The clutches were slipping with the dex6 causing it to shed and burn material and turn the fluid black.


What component or components in DexronVI could possibly cause this?

 

[vssjim]

I know that they always say you can use 6 in older cars but I always use Dexron 3 in 2005 and back and Dexron 6 in 2006 and up unless the car or light truck states in TSB to ust Dexron six in an older vehicle for a reason.

 

[MolaKule]

Originally Posted By: MolaKule


Quote:
sdowney717: If you have an older transmission, then stick with the older fluid type dex3.

The clutches were slipping with the dex6 causing it to shed and burn material and turn the fluid black.


What component or components in DexronVI could possibly cause this?


Jim, I realize it is up to the owner to determine what they think is proper for them.

But I would like to have people explain cause-and-effect when it comes to transmission failures, and not make sweeping statements without proof.

 

[MolaKule]

For those of you who might have a further interest in the development of DexronVI, I suggest the SAE paper by the chemists who developed it:

SAE 2008-01-1728 by Samuel H. Tersigni, et. al.,

A New Automatic Transmission Fluid with Extended Friction Durability and Minimal Temperature Dependence

The particular fluid discussed in this paper was developed for the ASIAN transmission market but it is essentially a DexronVI.

BTW, it is very readable and has a lot of color graphs and figures displaying friction coefficients with temperature, test duration, etc.

 

[Hollow]

I contacted both Valvoline and Subaru on what fluid I should use in my 2003 Outback's auto. The original spec was Dex III, which is now moot.

Valvoline said Dex VI is always backwards compatible.

Subaru said not to use Dex VI but to use a Dex/Merc fluid if I was not buying Subaru ATF.

I ended up with Maxlife Dex/Merc as it was recommended for the older 4EAT like I have on several forums.

 

[04SE]

Originally Posted By: MolaKule
For those of you who might have a further interest in the development of DexronVI, I suggest the SAE paper by the chemists who developed it:

SAE 2008-01-1728 by Samuel H. Tersigni, et. al.,

A New Automatic Transmission Fluid with Extended Friction Durability and Minimal Temperature Dependence

The particular fluid discussed in this paper was developed for the ASIAN transmission market but it is essentially a DexronVI.

BTW, it is very readable and has a lot of color graphs and figures displaying friction coefficients with temperature, test duration, etc.


Is there a site to read it without paying $24?

 

[MolaKule]

No. The SAE, like the ASME, STLE, and AIAA are private institutions for reviewed journals and charge for each paper.

Mola

 

[Whitewolf]

Originally Posted By: MolaKule
No. The SAE, like the ASME, STLE, and AIAA are private institutions for reviewed journals and charge for each paper.

Mola


That's correct Mola, no legal way around it. Another paper dealing with DEXRON-VI development is SAE 2006-01-3242.

 

[MolaKule]

Tribology International and others ask for $35.00 and up for one paper so I think the SAE prices are pretty good, comparatively speaking.